This invention relates to a sugar cane piler having a mechanical spring suspension device in place of the conventional chain used in known sugar cane pilers.
The mechanical spring device decreases by about 80% the force with which the tips of the piler act on the ground, thus obtaining a good flotation of the piler on the ground surface. By reducing the force of interaction between the piler and the ground, soil penetration by the piler's tips is decreased resulting in less contamination of the cane with stones, soil and other extraneous materials during bundling of the cane. Destruction of the cane's roots by the piler's tips is also avoided. The mechanical suspension device is characterized by having a cylinder closed at both ends, in which is located a previously compressed spring that is coupled to a rod which, in turn, is connected at one end to a plate and at the other end to a yoke.
Conventional sugar cane pilers have a rigid construction and consist of a pair of spaced apart vertical plates cut in the form of parabolic or eliptical curves, with tips at the ends. These plates are welded to a frame structure formed of lateral and longitudinal tubes. The frame is articulated to the main frame of the machine and suspended by a chain connected to an articulated arm that is actuated by a hydraulic cylinder. The lowest position of the piler is limited by the cylinder's stroke and the length of the chain. During cane bundling the force of interaction between the piler and the soil is so high that it is difficult to achieve a floating effect so the piler's tips tend to penetrate into the ground.
This penetration of the piler's tips causes contamination of the cane with stones, soil and other undesirable materials. There is also the danger of uprooting and destroying the cane stumps.
Many attempts have been made to try and reduce soil penetration by the piler's tips and to increase the flotation effect. One of the most common methods is to mount skids on the piler to reduce soil penetration by the piler's tips and improve the piler's floating effect. However, this doesn't occur because the skids have to have a large contact surface between the piler and the soil in order to effectively reduce penetration.
Some sugar cane loaders use an additional chain to reduce soil penetration when the ground is uniform, but the floating effect is still poor and when the ground is uneven, some of the cane is left on the ground without bundling.
Many inventions have been patented with the purpose of achieving a better piler floating effect. In U.S. Pat. No. 4,614,476, the piler consists of two parts: one upper rigid part as in the conventional design and a lower part which can be moved with respect to the upper part. Since the lower part comprises only a small proportion of the mass of the whole piler, it acts on the ground with a relatively small force. But since only the lower part floats, the floating effect in this design is satisfactory.
The above patent discloses many design alternatives for the two-part piler, but in practice no solution has been successful.
Problems caused by the rigidity of the lower part as well as the introduction of stones and soil between the piler's movable parts have been the main factors why this two-part piler has not been successful. Also this design requires a high investment cost because the whole conventional piler must be replaced by the new one.
U.S. Pat. Nos. 4,609,318; 2,674,380; and 2,874,854 show pilers where some elements have been added to the piler to help in bundling the cane. Those elements can perform oscillatory, linear or rotary movements. The most interesting solution appears to be a rotary mechanism adapted to the conventional piler, where toothed wheels mounted outside the walls of the piler help to bundle the cane. With this solution, the reaction force of the cane on the piler is reduced and, in turn, the force of penetration by the piler's tips is reduced. However, this design does not reduce the soil penetration force provided by the piler's own weight. Besides it is more expensive, because of the use of additional hydraulic motors. Moreover, it is not recommended for use in stony fields.